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Acta Physiol (Oxf). 2013 Dec;209(4):283-94. doi: 10.1111/apha.12174.

Acute molecular responses in untrained and trained muscle subjected to aerobic and resistance exercise training versus resistance training alone.

Author information

1
Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden; Department of Laboratory Medicine, Division of Clinical Physiology, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden.

Abstract

AIM:

This study assessed and compared acute muscle molecular responses before and after 5-week training, employing either aerobic (AE) and resistance exercise (RE) or RE only.

METHODS:

Ten men performed one-legged RE, while the contralateral limb performed AE followed by RE 6 h later (AE+RE). Before (untrained) and after (trained) the intervention, acute bouts of RE were performed with or without preceding AE. Biopsies were obtained from m. vastus lateralis of each leg pre- and 3 h post-RE to determine mRNA levels of VEGF, PGC-1α, MuRF-1, atrogin-1, myostatin and phosphorylation of mTOR, p70S6K, rpS6 and eEF2.

RESULTS:

PGC-1α and VEGF expression increased (P < 0.05) after acute RE in the untrained, but not the trained state. These markers showed greater response after AE+RE than RE in either condition. Myostatin was lower after AE+RE than RE, both before and after training. AE+RE showed higher MuRF-1 and atrogin-1 expression than RE in the untrained, not the trained state. Exercise increased (P < 0.05) p70S6K phosphorylation both before and after training, yet this increase tended to be more prominent for AE+RE than RE before training. Phosphorylation of p70S6K was greater in trained muscle. Changes in these markers did not correlate with exercise-induced alterations in strength or muscle size.

CONCLUSION:

Concurrent exercise in untrained skeletal muscle prompts global molecular responses consistent with resulting whole muscle adaptations. Yet, training blunts the more robust anabolic response shown after AE+RE compared with RE. This study challenges the concept that single molecular markers could predict training-induced changes in muscle size or strength.

KEYWORDS:

concurrent exercise; gene expression; human skeletal muscle; mammalian target of rapamycin; p70S6 kinase

PMID:
24112827
DOI:
10.1111/apha.12174
[Indexed for MEDLINE]

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